Pitch-based porous polymer beads for highly efficient iodine capture

Area of Science:

• Materials Science
• Environmental Chemistry
• Nuclear Engineering

Background:

• Efficient capture of volatile radioiodine is critical for spent fuel reprocessing safety.
• Existing methods face challenges in stability and capacity.

Purpose of the Study:

• To synthesize and evaluate novel composite beads for volatile iodine and methyl iodide removal.
• To assess the stability and performance of these beads under harsh conditions.

Main Methods:

• Synthesis of millimeter-scale pitch-based hyper-cross-linked porous polymers@polyethersulfone (PHCP@PES) composite beads.
• Characterization of bead structure and porosity.
• Testing of iodine and methyl iodide uptake capacities.
• Evaluation of material stability in 3 mol/L nitric acid.

Main Results:

• PHCP@PES beads demonstrated high uptake capacities: 770.0 mg/g for iodine vapor and 186.5 mg/g for methyl iodide.
• Uptake capacities remained largely stable after treatment with 3 mol/L nitric acid (744.5 mg/g for iodine vapor and 180 mg/g for methyl iodide).
• The interconnected pore structure facilitates rapid physical capture.

Conclusions:

• PHCP@PES composite beads are effective for capturing volatile iodine and methyl iodide.
• The material exhibits excellent acid and thermal stability, along with good mechanical properties.
• PHCP@PES presents a promising, low-cost candidate for radioactive iodine removal from exhaust gas streams in nuclear fuel reprocessing plants.